An Unlikely Guest
by SherLoki in the TARDIS
Summary: Sherlock accepts the help of an unlikely source, hoping that it will end with Moriarty behind bars. However, what starts off as purely business may spawn into a strong friendship, and perhaps something more. Takes place during A Scandal in Belgravia, starting off in that little break between The Pool Scene and Buckingham Palace. Sherlock and OC.
1. Chapter 1: The Client

Sherlock sat in his chair, his violin spread on his lap. He held the bow in both his hands, using both of his index fingers to hold it, and looking through the small gap between the wood and the string. John was out getting groceries. They had run out of milk again, caused once more by one of Sherlock's experiments. John was upset with him, as it was the third time this week, but it wasn't Sherlock's fault that milk held so many different experiments. At least, that was his excuse to John.

He sat tapping his foot. The client he was supposed to meet was taking a while to get here, and he couldn't take it much longer. He sighed in exasperation and got up angrily. _I don't have time for this_, he thought as he started pacing.

A knock came at his door. Mrs. Hudson peeked her head in, and Sherlock gave her a look as if saying, "Well, where is she?"

"Your client is here, Sherlock," Mrs. Hudson said.

"Thank you, Mrs. Hudson," he said, with a fake smile.

She moved out of the way to reveal his client. Sherlock quickly analyzed the woman, but there wasn't much to tell. She hid it all so well. She a tall, slender woman with longish auburn hair, pulled up in a ponytail that shortened it quite a bit. But it wasn't an uptight ponytail; the one that uptight business women wear, for her long bangs were swept across behind one ear. Her brown eyes were scanning him over as well, taking him back a bit. She was dressed almost like him, too, with a dark purple shirt and jet black dress pants. She gave him a smirk, then spoke.

"I'm sorry I'm late," she said, her voice somehow different than what he had expected. It was a bit...darker, a bit more grave than what he thought.

She walked over to a chair that was set in the middle of the room, her shoes clicking slightly as she walked. She sat and started fiddling with her cuffs. He walked around her, trying to read her over. From what he could tell, she was quiet, intelligent, clean. She was the youngest child in her family, chances are a twin. She was semi-professional, willing to break some rules to get what she wanted. She was calm, relaxed. But that was it. He couldn't tell if she was married, divorced, had pets, or her intentions. But there was something about her, something that he wasn't quite sure of, that made her one of the most interesting people he had met.

"So..." Sherlock said, trying to get her to reveal her name.

"Jane," she stated.

"Jane. Is it just Jane?" He asked.

"For now," she smirked again.

"So, Jane, why are you here?"

"I believe that I can be some assistance to you. I understand that you are having some difficulty dealing with," she paused, trying to find the right words, "an acquaintance of mine."

"And that would be?" Sherlock pressed.

"Jim Moriarty," she said, with a slight hint of hatred in her voice.

He stopped pacing and looked at her. This was something that definitely caught him off guard. How can she possibly know who he is? Did she work for him? Was she his lover? Was she is wife?

"If your wondering how I know him, I thought you'd already came to that conclusion."

"Say I didn't know..."

"What do you know about me, Mr. Holmes?" she asked.

That was a very good question. She didn't give away as much as he hoped, but maybe that was her intention. She was growing impatient with him, he could tell that much. So, he did what he knew best. Observe...and improvise.

"Well, I know that you are reserved and quick-witted. I know that you have an older sibling or two, and probably a twin, judging this on the way you present yourself. You are relaxed, but not used to being around people, again, by the way you present yourself. You don't let your feeling show, unless it's to someone you trust. You are vastly intelligent, and can read people and places with just a glance; you see everything. You are in a career that no one else is in, because no other career path fit you. You play an instrument, a stringed instrument, judging by the small calluses on your fingers. No pets, lives by yourself, though looking for someone to live with-you may want to tuck in that number from your pocket. You are-"

"Just like you," she finished.

"Almost," he said, smirking a little, "And, I can also tell that Jim Moriarty is more than just an acquaintance. Am I right?"

She smiled, "You're not wrong."

He smiled, too, "Yes. So how exactly do you know him?"

"You still haven't figured it out?"

"Amuse me."

"You obviously didn't look well enough."

"What do you mean?" Sherlock asked, frowning slightly.

"Look at me. Who do I remind you of? Not my personality, but my features."

He looked. Then it hit him. Her eyes. He had seen those eyes before. They were the eyes that had haunted him for months, but on someone else's face. The face of evil itself.

"It's not an easy thing to admit, having a twin brother who's a murderous psychopath," she said quietly, staring at her lap.


	2. Chapter 2: Sudden Realization

Sherlock stumbled a bit. He wasn't sure how to react. The fact that Moriarty's sister was sitting in his room gave him a chill up his spine. It would be like if Mycroft was joining sides with Moriarty. He was afraid, yet comfortable. He knew that she wasn't here to do harm, but he couldn't help but think that Moriarty was using her to get to him. Or that she was going to take over her brother's place if something should happen.

"If your wondering if I turned out like him, the answer is no," she said, "And now that the penny's hit the ground, I might as well tell you. My name is Jane Moriarty. I have two older brothers, Jim being only minutes older."

Sherlock said nothing. Only listened. He didn't know what to say. Finally, after much thought, he finally spoke.

"So, what made you decide to help me?"

She smiled a little and shifted. She felt just as odd about the whole affair as he did. She looked at him an said, "That's the question, isn't it? The million dollar question. Why would the sibling of your arch rival be sitting at your flat offering her services in catching him? It's a fairly simple answer."

"Which is?"

"I don't want to see anyone else get hurt."

He stopped and looked at her. She had a look of general concern. And something about that look of concern made him want to trust her, but yet put him on edge.

"How often do you keep in contact?" Sherlock asked.

"Not as often as you would think. I haven't talked to him in a month. That was the first I'd seen him in five years, and the first time I'd talked to him in four."

"What did he say to you?"

"He said he was planning something. He didn't get too specific..."

Sherlock nodded. She was hiding something. But they didn't have much time to themselves. Sherlock heard a taxi pull up, and a back door shut.

"One last thing, how do I know that I can trust you?"

"Look," she said, anger slowly creeping into her voice, "I know how this looks, but just because he's my brother, doesn't mean that I don't want him to get what he deserves. I wouldn't have came here if I wasn't desperate. I would have tried going to the police, but you know how Scotland Yard is. They're not willing to do anything unless you have solid evidence. And it doesn't help that I'm related to a convicted felon, either. And once they know that I've talked to him, they would use me as a tool to get bring him in. Even then, it wouldn't do much good. Jim knows how to manipulate people, how to pull at people's strings, and he would be out in less than two hours. He would be back to terrorizing not just you, but all of London. Not to mention myself. Do you want to know why you should trust me? The truth is you can't. You'll never fully trust me, because I'm his sister. And though you won't admit it, that's the only reason you're not entirely trusting me at this moment," she paused and looked at the door. John's footsteps were near the door now, and she sighed and stood up.

"I guess I should be leaving," Jane said.

"Sit down," he said. And she did.

The door opened and John walked in, arms full of groceries.

"Would it kill you to at least open the door for me, Sherlock?" he said from behind the large bags. He walked into the kitchen and started putting them away. Jane looked up at Sherlock, a small smile of amusement on her face. He smiled, too. He couldn't help but not trust her. But he wouldn't tell her that. Not now.

"What took you so long, John?" Sherlock asked, pretending Jane was not in the room.

"What took me so long? Well, where do I begin-" He turn around and stopped, only to see Jane sitting on the chair and Sherlock standing next to her. Both of them had a grin on their face.

"Oh. Sorry. I didn't realize-" John said, a slight look of embarrassment spreading across his face.

Sherlock smiled and nodded, as a way of saying that John was forgiven, and said, "John, this is Jane," he then looked at her and continued, "and she's going to help us with London's pest problem."


	3. Chapter 3: Can We Trust Her?

"Sorry, what?" John asked, slightly confused.

"She offered to help us with Moriarty," Sherlock said, amazed by his friend's cluelessness.

John nodded, still unsure of the whole situation. There had been some strange people coming through in the last few months, but none of them had offered to helped them with anything. Rather, the clients had always asked for their help. It was odd that someone would come in here, offering to help stop Jim Moriarty.

"Umm," Jane said, getting up from her chair, "Do you mind if I use your restroom?"

"Down the hall to the left," John said, nodding pointing towards the right hallway. She smiled and thanked them, then proceeded to walk down the hall.

"Alright, Sherlock," John said, "Why is she really here?"

"I told you," Sherlock said, quickly and indifferently, "She offered to help with Moriarty."

"There's something you're not telling me. Who is she?"

"Her name is Jane."

"Jane who?" John asked, his temper rising.

Sherlock sighed, "Jane Moriarty."

John tried to say something, but nothing came to mind. Finally, after a while of trying to speak, only words that came out were, "You're joking."

"No, I'm not," Sherlock said in that same indifference. His voice hadn't risen throughout this entire conversation. It was as though he had planned it through before John had walked through the door. And John wouldn't have been surprised if that was the case.

"How can we trust her?" John said, lowering his voice so the woman in the loo wouldn't hear, "How can we...how is she related to him? Is she his wife? What exactly is she to him?"

"Sister," Sherlock said, "Twin sister."

"Twin? Well, isn't that nice? You're going to have Moriarty's sister help us? Do you realize that you're taking the advice of the woman whose brother almost tried to kill us in an abandoned swimming pool?!"

"What choice do we have?" Sherlock said, quietly, "Nothing else has worked."

"We'll do what we've always done!" John said, "We'll figure something out on our own! Solve cases, find leads, lay low for a while."

"Doing what we have been doing hasn't been working," Sherlock said, "And besides, she's the best lead we have."

"Just like that," John huffed, "You're willing to trust this girl just like that? Just because you think she can bring you Moriarty in chains?"

"Yes," Sherlock said, "I do trust her. Not completely, but enough."

John stared at him incredulously. Finally, after a few moments had passed, he spoke.

"You're a bloody idiot, you know that?"

Sherlock smirked as he saw Jane walk into the main room with his peripheral vision. He watched as she sat down in one of the chairs facing the two men. She gave them a nervous smile and brushed some of her hair out of her face. Her eyes gravitated to the ground when John glared at her. The tension in the room was thick. It seemed that the harder John would glare at Jane, the more interested she became in the pattern of the carpeting. It wasn't until John had decided to go to his room that Jane became a bit more relaxed.

"You'll have to excuse my colleague," Sherlock said, sitting in the chair across from hers, "Our last run in with your brother was rather unpleasant."

Jane smirked, "Jim does tend to have that effect on people."

Sherlock smiled, then grew serious, "So...the plan that your brother said he had in mind?"

She sighed, "Like I said, he didn't say much. He said that he was going to destroy you. He didn't say how, or why for that matter, just that it was very long and intricate."

"Anything else?"

"He said that...after he was finished with you...that he'd bring me down, too," she said slowly. There was no fear in her voice, which was slightly surprising to Sherlock. He figured that she would show more emotion than what she has. Maybe she was more like Sherlock than he had thought.

"Why you?"

"I don't know. He's always resented me. Even when we were kids. I never fully understood why, and I still don't."

Sherlock closed his eyes and drew his fingertips to his mouth, "Do you know where he is?"

"Not at the moment, but," she said, pulling out something from her pocket, "he did mail me this." She placed it in front of Sherlock.

He picked up the small envelope. He pulled out a picture of three children standing with their arms wrapped around each other's shoulders. There was a girl on the left, with her hair falling freely across her face, a boy in the middle, who seemed to be the oldest out of them, and a boy on the right, with short hair and dark eyes. They were standing in front of a rather large house, but it looked as though they were in their backyard. He assumed that this was a picture of the Moriarty children, with Jane and Jim on either side of their eldest brother. It almost surprised him, seeing Jim Moriarty as a child. He could hardly picture Moriarty being a carefree child, and it was a little off putting to see him like that.

He was more surprised, however, by the small hole burned in the photograph, almost exactly where the girl's heart would be.

He put the photograph back in the envelope and handed it to her. She placed it back in her pocket. Sherlock felt sympathetic to her, or, at least something close to sympathy.

"Other than the photograph, has your brother tried to contact you in any way?"

She shook her head, "No. That's the most recent. I received it a little over a week or so ago."

"What made you decide to come to me?" Sherlock asked. The question had been gnawing at him for a while, and he felt now was as good of time as any to ask.

"I figured that maybe, if we worked together, it might just be enough to keep him behind bars," she said.

Sherlock nodded. He thought he heard John's door open and shut, and he heard the sound of his footsteps. He felt John glaring at the two of them as he passed, and he hoped that he would give them some privacy. John was just about to say something when Sherlock's phone rang. He quickly pulled it out of his pocket and answered the call.

"Ah. Hello, Lestrade," Sherlock said, getting up. He walked down the hall that John had just came out of, hoping to get a little privacy.

Jane glanced at the floor, and when she looked up, she saw John sitting where Sherlock, until moments ago, had been sitting.

"Alright, Miss Moriarty," the man said, leaning in menacingly, "I don't care that you've convinced Sherlock into believing your little story. I don't care that you made him believe that you're the victim in all of this. I don't even care that you're still trying to play the victim to me. But if you're planning on gaining our trust and then selling us out or...or betraying us in any way, you'd better hope that your brother gets to you first because I will show no mercy. So, if you are planning something, and you're not here doing what you say you're doing, you best walk out that door right now and never come back, because I will never forgive you if you harm Sherlock and I, and I will not rest until you've gotten what you deserve. Do you understand?"

Jane looked in his eyes. They were cold, but yet heated and angry at the same time. They were both calm and full of rage, emotionless yet full of repulsion. And all of this emotion was directed towards her. It terrified her, knowing that someone could be this sickened by her, just because she had the same parents as Jim Moriarty.

Jane didn't say anything, hoping that that would pass as an answer.

"Good," John said, getting up, "Glad we're on the same page."

Just then, Sherlock walked into the sitting room. Jane turned her gaze to Sherlock, trying to ignore the fact that John was still staring at her.

"John, Jane. Grab your coats," Sherlock said, walking across the room to grab his scarf.

"Why?" John asked, as Sherlock quickly looped his scarf around his neck.

"That was Lestrade," Sherlock said, who was now heading towards the door to retrieve his overcoat, "He says he's got a murder he wants me in on. He says that Moriarty might be involved."

"Why is she coming?" John asked. Jane felt the acidity that John placed in the word "she", but she didn't know if Sherlock had caught it or not

"Because we need her," Sherlock said, his hand placed on the door, "Now come on."

John sighed and grabbed his coat. He quickly put it on and walked out the door that Sherlock was currently holding open.

Jane, too, got up from her chair and grabbed her coat. As she walked downstairs to the cab she hoped that working with Sherlock Holmes would go a lot smoother than what this morning had.


End file.
